Chapter 1: DC and Switching Characteristics of HardCopy III Devices

1–23

Glossary

© December 2008

Altera Corporation

HardCopy III Device Handbook, Volume 3

S

SW (sampling

window)

The period of time during which the data must be valid in order to capture it correctly. The

setup and hold times determine the ideal strobe position within the sampling window.

Figure 1–5. Timing Diagram

Single-ended

Voltage

Referenced I/O

Standard

The JEDEC standard for SSTl and HSTL I/O standards defines both the AC and DC input

signal values. The AC values indicate the voltage levels at which the receiver must meet its

timing specifications. The DC values indicate the voltage levels at which the final logic state

of the receiver is unambiguously defined. Once the receiver input has crossed the AC value,

the receiver is changed to the new logic state.

The new logic state is maintained as long as the input stays beyond the DC threshold. This

approach is intended to provide predictable receiver timing in the presence of input

waveform ringing.

Figure 1–6. Single-Ended Voltage Referenced I/O Standard

T

t

C

High-speed receiver and transmitter input and output clock period.

TCCS

(channel-to-

channel-skew)

The timing difference between the fastest and the slowest output edges, including t

CO

variation and clock skew, across channels driven by the same PLL. The clock is included in

the TCCS measurement (refer to Figure 1–5 under S in this table).

t

DUTY

HIGH-SPEED I/O Block: Duty cycle on high-speed transmitter output clock.

Timing Unit Interval (TUI)

The timing budget allowed for skew, propagation delays, and data sampling window. (TUI =

1/(Receiver Input Clock Frequency Multiplication Factor) = t

t

FALL

Signal high-to-low transition time (80-20%)

t

INCCJ

Cycle-to-cycle jitter tolerance on PLL clock input

t

OUTPJ_IO

Period jitter on general purpose I/O driven by a PLL

t

OUTPJ_DC

Period jitter on dedicated clock output driven by a PLL

t

RISE

Signal low-to-high transition time (20–80%)

U

——

Table 1–33. Glossary Table

Letter

Subject

Definitions

Bit Time

0.5 x TCCS

RSKM

Sampling Window

(SW)

RSKM

0.5 x TCCS